Broken exhaust header bolt removal questions.

If the engine is already removed, you do have one more reliable option. For a reasonable fee a good machine shop will EDM the old bolt out, without any damage to the head. That is the real "official" standard technique that is employed after a reverse-screw drill or extractor fail or are not trusted. It's pretty foolproof with a competent operator, and the price is usually reasonable. No high heat involved.

Stu and others get this welding trick to work, but the aluminum will conduct the welding heat away pretty fast, so you need a LOT of current. And melting steel inside of aluminum threads definitely can distort the aluminum threads. So dialing in the correct current could be critical.

The EDM method is much safer and more reliable. Find a big machine shop with EDM equipment. It slowly erodes the steel regardless of its hardness, until there's just a spiral of thread left, which comes out easily. I really recommend EDM before it gets too screwed up with welding attempts. It's the more "correct" fix. Of course, anything that works is welcome...but that's my advice.

RXF

I used to do this for a living.

trust me a screw extractor of any description is not going to move it and neither is any penetrant you could imagine.


Jimmy

if all else fails the easy way is to grind the side out of the boss and puch the stud out sideways.

its a simple task then to tig the damage back up and redrill the hole into the fresh ali and rethread it.

a welding shop or a boat repair place can ali weld it .

spark discharge units are pretty thin on the ground in the southern hemisphere.

Bummer. EDM equipment is pretty common stuff here, perhaps because of the now-declining aircraft & aerospace industry. It was pretty common in the northern Midwest too. Any broken bolts, I'd just routinely let someone else fix for a twenty dollar bill, but it might be more now.

If you do break a long hard extractor off inside the shaft, don't freak out; you can crack it up further or again EDM doesn't care how hard it is, it erodes thru hard steel just fine.

But reverse-screw drills are the standard first attack, and work surprisingly often. Just start with making a flat surface and center-punch the exact center, and don't let the drill drift around. As you change to larger and larger reverse drill bits, sometime before you're into the threads the whole thing often comes out. There's another art in choosing the right size drill step increments...at first you increment slowly and feed really slowly with lots of oil. Then you may want to go to a larger size and higher speed so that the drill suddenly seizes onto the bolt with a lurch and unscrews it! Of course, again there's the risk of breaking off a hard drill bit but you can usually get it out.

You can try calling around and finding out who has EDM equipment. I've even considered making my own.